I guess it all depends on what kind of an army you wanna play.
Do you wanna go
magic? Fine, buy a slann and some more temple guard. One or two skink priests is good to have too, as vassals. They can also carry a dispel scroll or/and the cube of darkness from our army book. They can also channel dice.
Tetto eko works a lil like a slann but unfortunately only lvl2.
Fast and fighty? Skip the slann and fill up lord and part of hero slot with old bloods and scar vets on cold ones. Under the tactics index are at least one big thread covering different builds. A solid build for your general would be "Old blood, cold one, armor of destiny, dawnstone and a great weapon". That will give him a 1+ rerollable armor save and a 4++ ward save. Last game I killed a 500+ points Great unclean one with a build like that (with a lot of luck).
Anyway, point is that you put 4-5 scar vets and old blood on cold ones and then have them in a unit of cold one cavalry. The 8 ones you get from the battalion will be a lil on the low side. I would recommend the unit to be 5*3 ranks in total. So if you go with 4 characters it should be 10 rank and file cav and one champ. Your front rank should be filled up with characters for heavy hitting. Piranha blade on one of them could be very useful. Its a lot of points in a bus like this so be a lil careful with how you use it. At the same time the point is to reach combat quickly and don't be too afraid to loose a few rank and file. They're job is mainly too provide look out sir for your characters during transport to close combat.
Hmm, I guess that you understand by now which one I like.
Oh, and don't forget to save a few points in the hero slot for 2 skink priests. In this bus build lore of beast is very good. Just keep your skinks in one or two skirmish units within 12 inch from your characters in the bus. Reason for that is that most buff spells have a 12 inch range.
You can also go with dual carnosaurs. One for the Old blood and one for the scar vet. There is an awesome thread for that in the tactics section.
After that you must fill up the core requirements. I recommend 3-4 Skirmisher units. Either a saurus block or skink cohort with kroxigor combined unit.
Special, its all about what flavor you like. you can go with flyers. Or a bastiladon with solar engine ( skip him if you go with a slann though, you will probably wanna use you power dice for the slann).
Rare, ancient stegadon with sharpened horns is good. Just be very careful with it. Its important that you get the charge since that is where he really shines. With the sharpened horns you don't have to be afraid to charge monsters. It eats them alive when causing multiple wounds. Salamanders are good too, but they shine against big blocks of infantry.
Ok, this is my view of it. I am sure other people would recommend something else. I recommend you to read a lot in the tactics section. You can also watch battle reports on youtube.
Magic heavy bat reps: https://www.youtube.com/channel/UCQxOaZ4mJoTu4Adi1GcvKkw
Cold one bus bat reps: https://www.youtube.com/channel/UCOcGMWynVCEN1p0l0cw8_8g
If you have more questions just shoot.
/Crillaz
